Soirée Guava et Lombok avec Thierry Leriche

Milou fait un régimeGuava - Lombok

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NORMANDY JUG

Thierry Leriche-Dessirier

icauda.com

Consultant JEE freelance Professeur de Génie Logiciel à l’ESIEA Rédacteur pour Programmez Rédacteur pour Developpez.com

@thierryleriche

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13 OOO OOO pages vues par mois

5 500 000 visites par mois

2 500 000 visites uniques par mois

5 000 messages forum par jour

Agen

da

Milou est trop lourd (intro)

Lombok (et Lombok-pg) en action

Tour d’horizon de Guava

Milou est trop lourd (et doit faire un régime)

I am Milou

public class Dog {

private Integer id ; private String name ; private String fullName ; private SexeEnum sex ; private Date birthday ; private String race ; private Boolean lof ; private Double weight ; private Double size ; private List<String> colors ;

...

DO

G 5

id name fullName sex birthday race lof weight size Colors

Constructeurs Getters / setters toString () equals () hashCode () compareTo ()

clic clicdémo



public class Dog implements Comparable<Dog> {

...

@Override public int compareTo(Dog other) { int result = 0;

result = name.compareTo(other.name); if (result != 0) { return result; }

... }

Code très limite… NPE ?...



210 lignes10 attributs

210 lignes de code

10 attributs

Java

Va c

herc

her G

uava

toString () equals () hashCode () compareTo ()

Commons FAQ 1-2

Base

Objects

public String toString() { return "Dog [id=" + id + ", name=" + name + ", fullName=" + fullName + ", sex=" + sex + ", birthday=" + birthday + ", race=" + race + ", lof=" + lof + ", weight=" + weight + ", size=" + size + ", colors=" + colors + "]";}

Java

5 5

toString ()

Simple, efficace et bien pourri

public String toString() { StringBuilder sb = new StringBuilder();

sb.append(Dog.class.getSimpleName()) .append("[id=").append(id) .append(", name=").append(name) .append(", fullName=").append(fullName) ... .append(", colors=").append(colors);

return sb.toString();}

Java

5 5

toString ()

Mieux mais sans plus

public String toString() { return Objects.toStringHelper(this) .add("id", id) .add("name", name) .add("fullName", fullName) ... .add("colors", colors) .toString();}

Gua

va G

toString ()

Builder

public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false;

Dog other = (Dog) obj; if (birthday == null) { if (other.birthday != null) return false; } else if (!birthday.equals(other.birthday)) return false; if (fullName == null) { if (other.fullName != null) return false; ... } else if (!race.equals(other.race)) return false; if (sex != other.sex) return false;

return true;}

Java

5 5

equals ()

birthday, fullname, name, race et sex

Carrément illisible

public boolean equals(Object obj) { if (!(obj instanceof Dog)) return false;

Dog other = (Dog) obj;

return Objects.equal(birthday, other.birthday) && Objects.equal(fullname, other.fullname) && Objects.equal(name, other.name) && Objects.equal(race, other.race) && sex == other.sex;}

Gua

va G

equals ()


public int hashCode() { final int prime = 31; int result = 1;

result = prime * result + ((birthday == null) ? 0 : birthday.hashCode()); result = prime * result + ((fullName == null) ? 0 : fullName.hashCode()); result = prime * result + ((name == null) ? 0 : name.hashCode()); result = prime * result + ((race == null) ? 0 : race.hashCode()); result = prime * result + ((sex == null) ? 0 : sex.hashCode());

return result;}

Java

5 5

hashCode ()


public int hashCode() {

return Objects.hashCode(birthday, fullName, name, race, sex);}

Gua

va G

hasCode()


public int compareTo(Dog other) { int result = 0;

result = name.compareTo(other.name); if (result != 0) { return result; } result = fullname.compareTo(other.fullname); if (result != 0) { return result; }

...}

Java

5 5

compareTo ()

name, fullname, birthday, weight, size, race et sex

name.compareTo(other.name)

compareTo ()

other.name.compareTo(name)Vs

public int compareTo(Dog other) { return ComparisonChain.start() .compare(name, other.name) .compare(fullName, other.fullName) .compare(birthday, other.birthday) .compare(weight, other.weight) .compare(size, other.size) .compare(race, other.race) .compare(sex, other.sex) .result();}

Gua

va G

compareTo ()

name, fullname, birthday, weight, size, race et sex

Lom

bok

en action

Régime

Annotations de base

@NoArgsConstructor / @RequiredArgsConstructor / @AllArgsConstructor constructeurs

@Getter / @Setter @ToString @EqualsAndHashCode @Data @Getter + @Setter + @ToString + @EqualsAndHashCode + @RequiredArgsConstructor

Régi

me

clic clicdémo

Régi

me @NoArgsConstructor /

@RequiredArgsConstructor / @AllArgsConstructor

@Getter / @Setter @ToString @EqualsAndHashCode @Data

210 lignes de code

10 attributs

Java

12 lignes + 2-3 @ + compareTo()Lombok

name, sex

@RequiredArgsConstructor(staticName = "of")public class Dog {

private Integer id; @NonNull private String name; private String fullName; @NonNull private SexeEnum sex; private Date birthday; ...

Dog dog = Dog.of("Milou", MALE);

Fact

ory L

name, sex

private Dog(@NonNull final String name, @NonNull final SexeEnum sex) { if (name == null) throw new NullPointerException("name"); if (sex == null) throw new NullPointerException("sex");

this.name = name; this.sex = sex;}

public static Dog of(@NonNull final String name, @NonNull final SexeEnum sex) { return new Dog(name, sex);}

@RequiredArgsConstructor(staticName = "of")public class Dog {

private Integer id; @NonNull private String name; private String fullName; @NonNull private SexeEnum sex; private Date birthday; ...

Dog dog = Dog.of("Milou", MALE);

Fact

ory L

Trucs pratiques

Se simplifier la vie

@Cleanup @Synchronized @SneakyThrows @Log @Delegate

valPrati

que

public void lireJava6(String from) { InputStream in = null; try { in = new FileInputStream(from); byte[] b = new byte[10000]; while (true) { int r = in.read(b); if (r == -1) break; ... } } catch (Exception e) { ... } finally { if (in != null) { try { in.close(); } catch (Exception e) { ... } } ...

Ress

ourc

es 5

public void lire(String from) throws IOException {

@Cleanup InputStream in = new FileInputStream(from);

byte[] b = new byte[10000]; while (true) { int r = in.read(b); if (r == -1) break; ... }}Re

ssou

rces L

Délombok

Revenir sans la lib

Dél

ombo

k <properties> <lombok.sourceDirectory> ${project.basedir}/src/main/java </lombok.sourceDirectory>...

<build> <groupId>org.projectlombok</groupId> <artifactId>maven-lombok-plugin</artifactId> <executions> <execution> <phase>generate-sources</phase> </execution> </executions> ...

mvn lombok:delombok

java -jar lombok.jar delombok src -d src-delomboked

XML

Dél

ombo

k @Datapublic class Dog { private Integer id; private String name; private String fullName; private SexeEnum sex; private Date birthday; private String race; private Boolean lof; private Double weight; private Double size; private List<String> colors;}

5public class Dog { private Integer id; private String name; private String fullName; ... private List<String> colors;

public DogLombok() { }

@java.lang.Override @java.lang.SuppressWarnings("all") public boolean equals(final java.lang.Object o) { if (o == this) return true; if (o == null) return false; if (o.getClass() != this.getClass()) return false; final Dog other = (Dog)o; if (this.getId() == null ? other.getId() != null : !this.getId().equals(other.getId())) return false; ...

@java.lang.Override @java.lang.SuppressWarnings("all") public int hashCode() { final int PRIME = 31; int result = 1; result = result * PRIME + (this.getId() == null ? 0 : this.getId().hashCode()); result = result * PRIME + (this.getName() == null ? 0 : this.getName().hashCode());

mvn lombok:delombok

5

Lombok-pg

Annotations supplémentaires

@Action @Function @EnumId @Rethrow / @Rethrows @Singleton @AutoGenMethodStub @BoundPropertySupport / @BoundSetter @DoPrivileged @ExtensionMethod @ListenerSupport @WriteLock / @ReadLock @Await / @Signal / @AwaitBeforeAndSignalAfter @Sanitize.Normalize / .With @SwingInvokeLater / @SwingInvokeAndWait @Validate.NotEmpty / .NotNull / .With @VisibleForTesting

Anno

tatio

ns P

g @Builder @LazyGetter @FluentSetter @Predicate

@FluentSetter@Getterpublic class Dog {

private Integer id ; private String name ; private String fullName ;

...

DogLombok dog = new DogLombok();dog.name("Milou").sex(MALE);

Flue

nt

println( dog.getName()); // Milouprintln( dog.getSex()); // MALE

L

@Builder@Getterpublic class Dog {


...

Dog dog = Dog.dog().name("Milou").sex(MALE).build();

Build

er

println( dog.getName()); // Milouprintln( dog.getSex()); // MALE

L

@ExtensionMethod({ Dog.class, MyDogExtensionClass.class })public class DogWithExtension {

public void foo() { Dog milou = new Dog("Milou", 12.5, ...); boolean isTooFat = milou.isTooFat(); }}

class MyDogExtensionClass {

public static boolean isTooFat(final Dog dog) { double imc = dog.getWeight() / pow(dog.getSize(), 2); return 25 < imc; }}

exte

nsio

n L

Avec paramètres FAQ 9

http://blog.developpez.com/todaystip/p11165/dev/java/extensionmethod-de-lombok-pg/

Lombok or not Lombok ?

Avantages et inconvénients

Pro

/ Co

ns Byte code modifié Version en 0.x Documentation des prog ? Magique ?

Compacité Lecture simplifiée Code normée Délombok (pour essayer)

Gua

va

tour d’horizon

Factory Methods

Les choses que j’aime

List<Integer> primeNumbers = new ArrayList<Integer>();

Set<String> colors = new TreeSet<String>();

Map<String, Integer> ages = new HashMap<String, Integer>();Java

5 5< new Vs static factories >

Java

5

Map<String, List<String>> trucs = new HashMap<String, List<String>>();

Map<? extends Person, Map<String, List<String>>> trucs = new TreeMap<? extends Person, Map<String, List<String>>>();

Map<? extends Wrapper<String, Sex, Person>, Map<String, List<Set<Adress<String, Integer, Country>>>>> trucs = ...

dur d

ur ? 5



Map<String, Integer> ages = new HashMap<String, Integer>();5

< new Vs static factories >

Java

5

List<Integer> primeNumbers = new ArrayList<>();

Set<String> colors = new TreeSet<>();

Map<String, Integer> ages = new HashMap<>();Java

7

Qui utilise Java 7 en prod ?

7





Java

5Ja

va 7


List<Integer> primeNumbers = newArrayList();

Set<String> colors = newTreeSet();

Map<String, Integer> ages = newHashMap();Gua

va

Dès maintenant !

G



Map<String, Integer> ages = new HashMap<>();





Java

5Ja

va 7



Set<String> colors = newTreeSet();

Map<String, Integer> ages = newHashMap();Gua

va

Dès maintenant !

G



Map<String, Integer> ages = new HashMap<>();




var primeNumbers = new ArrayList<Integer>();

-> primeNumbers.size(); ...

Lom

bok


L

List<Dog> dogs = newArrayList( new Dog("Milou", 12.5, MALE, ...),

new Dog("Rintintin", 45.0, MALE, ...),

new Dog("Volt", 10.3, MALE, ...),

new Dog("Lassie", 45.0, FEMALE, ...),

new Dog("Pluto", 22.0, MALE, ...),

new Dog("Medor", 35.6, MALE, ...));

List

of d

ogs

G

[Milou, Rintintin, Volt, Lassie, Pluto, Medor]


Immutables

Pour que ça ne change pas

Quand ?immutable

Quand ?immutable

mutable

On se demande souvent si une liste doit être immutable mais c’est prendre le problème dans le mauvais sens. La plupart du temps, ce qu’il faut vraiment se demander, c’est si la liste a besoin d’être mutable.

Java

5 Set<Integer> temp = new LinkedHashSet<Integer>(Arrays.asList(1, 2, 3, 5, 7));

Set<Integer> primes = Collections.unmodifiableSet(temp);

< unmodifiables Vs immutables >

Java

5

Set<Integer> primes = ImmutableSet.of(1, 2, 3, 5, 7);

Set<Integer> temp = new LinkedHashSet<Integer>(Arrays.asList(1, 2, 3, 5, 7));

Set<Integer> primes = Collections.unmodifiableSet(temp);

Gua

va< unmodifiables Vs immutables >

G

Of

ImmutableSet.of(E e1)ImmutableSet.of(E e1, E e2)ImmutableSet.of(E e1, E e2, E e3)ImmutableSet.of(E e1, E e2, E e3, E e4)ImmutableSet.of(E e1, E e2, E e3, E e4, E e5)ImmutableSet.of(E e1, E e2, E e3, E e4, E e5, E e6, E...)

Ne prend pas de null

Of

ImmutableSet.of()

Vide

Map et List FAQ 4

< unmodifiables Vs immutables >

G

http://blog.developpez.com/guava/p10589/collection/title-212/

Java

5 public class Dog { private String name; ... private List<String> colors;

public Dog(String name, List<String> colors) { this.name = name; ... this.colors = Collections.unmodifiableList( new ArrayList<String>(colors)); }

public List<String> getColors() { return colors; }

5< Copie de défense >

Gua

va public class Dog { private String name; ... private ImmutableList<String> colors;

public Dog(String name, List<String> colors) { this.name = name; ... this.colors = ImmutableList.copyOf(colors); }

public ImmutableList<String> getColors() { return colors; }

G

Message clair

< Copie de défense >

Collections en plus

Multimap, Bipap, Multiset, Table

Java

5 Map<String, List<String>> dogFavoriteColors = new HashMap<String, List<String>>(); 5

< Multi Map >

List<String> milouColors = dogFavoriteColors.get("Milou");if(milouColors == null) { milouColors = new ArrayList<String>(); dogFavoriteColors.put("Milou",milouColors);}milouColors.add("Vert");

5

Java

5 Map<String, List<String>> dogFavoriteColors = new HashMap<String, List<String>>(); 5

< Multi Map >

List<String> milouColors = dogFavoriteColors.get("Milou");if(milouColors == null) { milouColors = new ArrayList<String>(); dogFavoriteColors.put("Milou",milouColors);}milouColors.add("Vert");

5G

uava Multimap<String, String> dogFavoriteColors =

HashMultimap.create();

dogFvoriteColors2.put("Milou", "Jaune");dogFavoriteColors2.put("Milou", "Rouge");

G

< Bi Map >

Gua

va BiMap<String, Dog> tatouages = HashBiMap.create();tatouages.put("ABC123", new Dog("Milou") );tatouages.put("MBD324", new Dog("Volt") );tatouages.put("JFT672", new Dog("Lassie") );

ABC123=MilouMDB324=VoltJFT672=LassieIl est possible de changer la valeur associée à une clé mais pas d'avoir deux clés avec la même valeur (IllegalArgumentException).

println( tatouages );

Une map bijective

{ABC123=Milou,MBD324=Volt,JFT672=Lassie}

G

println( tatouages.inverse() );{Milou=ABC123,Volt=MBD324,Lassie=JFT672}

< Multi Set >

Gua

va Multiset<Integer> ages = HashMultiset.create();ages.add(2);ages.add(3);ages.add(7);ages.add(11);ages.add(3);ages.add(5);

println( ages );

println( ages.count(3) )

[2, 3 x 2, 5, 7, 11]

2

G

< Table >

Gua

va // Sexe, couleur, nomTable<SexeEnum, String, String> dogTable = HashBasedTable.create();

dogTable.put(MALE, "jaune", "Pluto");dogTable.put(MALE, "blanc", "Milou");dogTable.put(MALE, "noir", "Medor");dogTable.put(FEMALE, "noir", "Lassie");dogTable.put(FEMALE, "blanc", "Pupuce");

G

< Table >

Gua



Map<String, String> maleRow = dogTable.row(MALE);println( maleRow )

{ jaune=Pluto, noir=Medor, blanc=Milou }

G

Map<String, String> femaleRow = dogTable.row(FEMALE);println( femaleRow )

{ noir=Lassie, blanc=Pupuce }

< Table >

Gua



Map<SexeEnum, String> blancColumn = dogTable.column("blanc");println( blancColumn )

{ FEMALE=Pupuce, MALE=Milou }

Map<SexeEnum, String> jauneColumn = dogTable.column("jaune");println( jauneColumn )

{ MALE=Pluto }

Base

Préconditions, joiner, splitter, optional

toString () equals () hashCode () compareTo ()

public class Dog {

private Integer id ; private String name ; private String fullName ; ...

public Dog(String name, String fullName, ...) { if(name == null) { throw new NPE("Le nom bla bla"); } if(fullName == null) { throw new NPE("bla bla"); } ...

this.name = name; this.fullName = fullName; ... }

DO

G 5< Preconditions >

import static com.google.common.base.Preconditions.*;

public class Dog {

private Integer id ; private String name ; private String fullName ; ...

public Dog(String name, String fullName, ...) {

this.name = checkNotNull(name, "bla bla"); this.fullName = checkNotNull(fullName, "bla bla"); ... }

DO

G G< Preconditions >

checkNotNull() NPEcheckArgument() IAEcheckState() ISE

Join

er String names = Joiner.on(", ") .join(newArrayList("Lassie", "Volt", "Milou"));

List<String> dogNames = newArrayList("Lassie", "Volt", "Milou");

StringBuilder sb = new StringBuilder();boolean first = true;for (String name : dogNames) { if(name != null || name.trim().isEmpty()) { continue; } if (!first) { sb.append(", "); }

sb.append(name); first = false;}

String names = sb.toString();

Java classique

G"Lassie, Volt, Milou"

Join


String names = Joiner.on(", ") .join(newArrayList("Lassie", "Volt", null, "Milou"));

NPE


Join



String names = Joiner.on(", ") .skipNulls() .join(newArrayList("Lassie", "Volt", null, "Milou"));

"Lassie, Volt, Milou"

NPE


G

Join



String names = Joiner.on(", ") .skipNulls() .join(newArrayList("Lassie", "Volt", null, "Milou"));

"Lassie, Volt, Milou"

NPE

String names = Joiner.on(", ") .useForNull("Anonymous")) .join(newArrayList("Lassie", "Volt", null, "Milou"));

"Lassie, Volt, Anonymous, Milou"


GG

http://blog.developpez.com/guava/p11054/base/joiner-pour-assembler-des-items/

Splitt

er Iterable<String> dogNames = Splitter.on(",") .split("Lassie, Volt, Milou");

[ "Lassie", "Volt", "Milou" ]

Splitt



Iterable<String> dogNames = Splitter.on(",") .split("Lassie, Volt, ,Milou");

[ "Lassie", "Volt", " ", "Milou" ]

Splitt





Iterable<String> dogNames = Splitter.on(",") .trimResults() .split("Lassie, Volt, ,Milou");

[ "Lassie", "Volt", "", "Milou" ]

Splitt





Iterable<String> dogNames = Splitter.on(",") .trimResults() .split("Lassie, Volt, ,Milou");

Iterable<String> dogNames = Splitter.on(",") .trimResults() .omitEmptyStrings() .split("Lassie, Volt, ,Milou");

G[ "Lassie", "Volt", "Milou" ]

http://blog.developpez.com/guava/p11045/annotation/splitter-pour-separer-des-items/

[ "Lassie", "Volt", "", "Milou" ]

Opti

onal

Wrapper Optional <T>

Dog dog = new Dog("Milou", ...);

Optional<Dog> opt = Optional.of(dog);

assertTrue( opt.isPresent() ); assertEquals( "Milou", opt.get().getName() );

Opti

onal





Optional<Dog> opt = Optional.absent();assertFalse( opt.isPresent() ); opt.get(); ISE

Opti

onal






Dog dog = null;Optional<Dog> opt = Optional.of(dog); NPE

Optional<Dog> opt = Optional.fromNullable(dog);

http://blog.developpez.com/guava/p11163/base/le-wrapper-optional-de-guava/

Opti

onal






Dog dog = null;Optional<Dog> opt = Optional.of(dog); NPE

Optional<Dog> opt = Optional.fromNullable(dog);

Dog dog = null;Optional<Dog> opt = Optional.fromNullable(dog);

Dog dog2 = opt.or( new Dog("noname", ...) ); assertEquals( "noname", dog2.getName() );

Functional Programming

todo

Super chien

Dog

public class SuperChien implements SuperHero {

private String surnom ; private double poids ; private Set<String> couleursCostume ; private Set<String> pouvoirs ;

...

Supe

r Chi

en 5

Les héros peuvent avoir plusieurs costumes donc je n’utilise pas un ImmutableSet. Idem pour les pouvoirs

dont la liste augmente avec l’expérience.

Tran

sfor

mati

on List<SuperChien> superChiens = Lists.transform(dogs, new Function<Dog, SuperChien>() { @Override public SuperChien apply(Dog dog) { SuperChien chien = new SuperChien();

chien.setSurnom("Super " + dog.getName()); chien.setPoids(dog.getWeight()); chien.setCouleursCostume(newHashSet(dog.getColors())) chien.setPouvoirs(newHashSet("Code en Java", "Vole")) ...

return chien; }});

[Super Milou, Super Rintintin, Super Volt, Super Lassie, Super Pluto, Super Medor]

< Transformation >

G

List<SuperChien> superChiens = Lists.transform(dogs, new Function<Dog, SuperChien>() { @Override public SuperChien apply(Dog dog) { SuperChien chien = new SuperChien(); ... return chien; } });

Vue (lazy) size / isEmpty dispo Pas pour traitements répétés FAQ 3

List<SuperChien> chiens = newArrayList(Lists.transform(...

ImmutableList<SuperChien> chiens =ImmutableList.copyOf(Lists.transform(...

Tran

sfor

mati

on< Transformation >

G

Filtr

e Predicate<Dog> malePredicate = new Predicate<Dog>() { public boolean apply(Dog dog) { return dog.getSex() == MALE; } }

Iterable<Dog> maleDogs = Iterables.filter(dogs, malePredicate);

< Filtre >

G

G[Milou, Rintintin, Volt, Pluto, Medor]

Filtr



Dog firstMaleDog = Iterables.find(dogs, malePredicate);

< Filtre >

G

G[Milou, Rintintin, Volt, Pluto, Medor]

GMilou

Filtr



Dog firstMaleDog = Iterables.find(dogs, malePredicate);

Dog firstMaleDog = Iterables.find(femaleDogs, malePredicate, DEFAULT_DOG );

Default dog

< Filtre >

G

GGMilou

[Milou, Rintintin, Volt, Pluto, Medor]

Pas

fluen

tPredicate<Dog> malePredicate = new Predicate<Dog>() { public boolean apply(Dog dog) { return dog.getSex() == MALE; }};

Function<FullDog, String> nameFunction = new Function<FullDog, String>() { public String apply(FullDog dog) { return dog.getName(); }};

Iterable<FullDog> maleDogs = Iterables.filter(dogs, malePredicate);

Iterable<String> maleNames = Iterables.transform(maleDogs, nameFunction);


< Fluent or not fluent ? >

GGG

Pas

fluen

tIterable<FullDog> maleDogs = Iterables.filter(dogs, malePredicate);

Iterable<String> maleNames = Iterables.transform(maleDogs, nameFunction);


List<String> maleNames2 = FluentIterable.from(dogs) .filter(malePredicate) .transform(nameFunction) .toImmutableList();

Flue

nt

Guava 12.0

< Fluent or not fluent ? >

G

G

http://blog.developpez.com/guava/p11092/annotation/fluentiterable-sur-mon-chien-guava/

Cache

todo

Web

Ser

vice public class DogService {

@Inject private PetShopWebService service;

public Integer getNumberDogsSoldYesterday() { return service.checkSales( "dog" ); }

< Memoization >

5

Web

Ser



public Integer getNumberDogsSoldYesterday() { return service.checkSales( "dog" ); }

< Memoization >

5Ca

che

man

uel

private Integer nbOfDogsSold;

public Integer getNumberDogsSoldYesterday() { if (nbOfDogsSold == null) { nbOfDogsSold = service.checkSales( "dog" ); } return nbOfDogsSold; }

5Double check null…

Gua

va public class DogService { @Inject private PetShopWebService service;

private Supplier<Integer> nbOfDogsSoldSupplier = Suppliers.memoize( new Supplier<Integer>() { public Integer get() { return service.checkSales( "dog" ); } });

public Integer getNumberDogsSoldYesterday() { return nbOfDogsSoldSupplier.get(); }

< Memoization >

G

Gua


private Supplier<Integer> nbOfDogsSoldSupplier = Suppliers.memoizeWithExpiration( new Supplier<Integer>() { public Integer get() { return service.checkSales( "dog" ); } }, 1, TimeUnit.DAYS );

public Integer getNumberDogsSoldYesterday() { return nbOfDogsSoldSupplier.get(); }

< Memoization >

G

Web

Ser



private Map<String, Dog> dogMap = Maps.newHashMap();

public Integer getDog(String name) { Dog dog = dogMap.get(name); if(dog == null) { dog = service.getAnimal( "dog", name ); // type-name dogMap.put( name, dog ); } return dog; }

< Cache >

5

Quid du timeout ? Max ?

Gua


private LoadingCache<String, Dog> dogCache = CacheBuilder.newBuilder() .maximumSize(2000) .expireAfterWrite(30, TimeUnit.MINUTES) .build(new CacheLoader<String, Dog>() { public Dog load(String key) { return service.getAnimal( "dog", key ); } });

public Integer getDog(String name) { return dogCache.get( name ); // + try-catch }

< Cache >

G

Hash

Fantôme

Has

h HashFunction hf = Hashing.md5();HashCode hc = hf.newHasher() .putInt(123) .putString("Milou") .hash();

byte[] bytes = hc.asBytes();

md5 Murmur3 128 bits Murmur3 32 bits Sha1 Sha256 Sha512 goodFastHash

G

Prép

arati

on int NB_OF_DOGS = 100000;List<Dog> dogs = newArrayList();Random rand = new Random();for (int i = 0; i < NB_OF_DOGS; i++) { Dog dog = new Dog(); dog.setName("abc" + rand.nextInt(999)); ... dogs.add(dog);}

dogs.add(milou);

boolean isInList = dogs.contains(milou);true (14 ms)

final Dog milou = new Dog();milou.setName("Milou");...

boolean isInList = dogs.contains(milou); false (14 ms)cont

ains

< Is in list ? >

5

5

Bloo

m fi

lter

Funnel<Dog> dogFunnel = new Funnel<Dog>() { public void funnel(Dogdog, PrimitiveSink sink) { sink.putString(dog.getName()) .putString(dog.getFullName()) .putString(dog.getRace()); }};

BloomFilter<Dog> bloom = BloomFilter.create(dogFunnel, NB_OF_DOGS, 0.01);

for (int i = 0; i < NB_OF_DOGS; i++) { ... bloom.put(dog);

bloom.put(milou);

boolean isInList = bloom.mightContain(milou);true (0 ms)

boolean isInList = bloom.mightContain(milou);false (0 ms)

< Is in list ? >

G

http://blog.developpez.com/guava/p11149/collection/bloom-filter-de-guava-13/

Guava 13

Guava or not Guava ?

Avantages et inconvénients

Pro

/ Co

ns Ne pas en abuser…

Utile Bonnes pratiques

LIEN

S @thierryleriche

Guava http://code.google.com/p/guava-libraries

Lombok http://projectlombok.org

Lombok-pg https://github.com/peichhorn/lombok-pg

ICAUDAhttp://icauda.comhttp://icauda.com/articles.html (articles)http://icauda.com/cours.html (slides)

Blog Guavahttp://blog.developpez.com/guava

« Simplifier le code de vos beans Java à l'aide de Commons Lang, Guava et Lombok »http://thierry-leriche-dessirier.developpez.com/tutoriels/ java/simplifier-code-guava-lombok (article)

MER

CI

FAQ

/ B

onus

1. Guava Vs Commons 2. Régime façon Apache 3. Fonctionnal prog Vs boucle for 4. Créer des Maps5. Charsets6. Converter Spring7. Orderings8. Licences9. Extension avec valeurs10. Chrono11. CharMatcher12. Impl13. And, or, in…14. Partition, limit15. Inférence de type16. Coût du bloom17. Ecrasement des getters existants

Guava Vs Commons ?

http://tinyurl.com/guava-vs-apache

1

Régime : la méthode Commons ?

2

public String toString() {

return new ToStringBuilder(this) .append("id", id) .append("name", name) .append("fullName", fullName) ... .append("colors", colors) .toString();}

toSt

ring

L


2

public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (!(obj instanceof Dog)) return false;

Dog other = (Dog) obj;

return new EqualsBuilder() .append(birthday, other.birthday) .append(fullname, other.fullname) .append(name, other.name) .append(race, other.race) .append(sex, other.sex) .isEquals();}

equa

ls L


2

public int hashCode() {

return new HashCodeBuilder(17, 37) .append(birthday) .append(fullname) .append(name) .append(race) .append(sex) .toHashCode();}

hash

Code L


2

public int compareTo(Dog other) {

return new CompareToBuilder() .append(name, other.name) .append(fullname, other.fullname) .append(birthday, other.birthday) ... .append(sex, other.sex) .toComparison();}

com

pare

To L

List<SuperChien> superChiens = newArrayList();for(Dog dog : dogs) { SuperChien chien = new SuperChien(); ... superChiens.add(chien);}

List<SuperChien> superChiens = newArrayList( Lists.transform(dogs, new Function<Dog, SuperChien>() { @Override public SuperChien apply(Dog dog) { SuperChien chien = new SuperChien(); ... return chien; } }));Tr

ansf

orm

ation

Fonctionnal prog Vs boucle for : quand ?

http://code.google.com/p/guava-libraries/wiki/FunctionalExplained

Vs3 G

G

Créer des Maps

4

of

public static final ImmutableMap<String, Integer> AGES = new ImmutableMap.Builder<String, Integer>() .put("Milou", 32) .put("Volt", 7) .put("Pluto", 37) .put("Lassie", 17) .put("Medor", 5) .put("Croquette", 8) .put("Loulou", 2) ... .build();

public static final ImmutableMap<String, Integer> AGES = ImmutableMap.of("Milou", 32, "Volt", 7, "Pluto", 37, "Lassie", 17);

Build

er

G

G

Charsets

5

Java

5

String name = "Milou";

byte[] bytes = name.getBytes(Charsets.UTF_8);

String name = "Milou";

try { byte[] bytes = name.getBytes("UTF-8");

} catch (UnsupportedEncodingException e) { throw new AssertionError(e);}

Gua

va

Ca n’arrive jamais cette exception

5

G

import org.springframework...Converter;

@Component("dogToChienConverter")public class DogToChienConverter implements Converter<List<Dog>, List<SuperChien>> {

public List<SuperChien> convert(List<Dog> dogs) { List<SuperChien> chiens = newArrayList(transform(dogs, new Function<Dog, SuperChien>() { public SuperChien apply(Dog dog) { ... return chien; } })); return chiens; }6

Converter Spring

Lazy or not lazy ?

G

Orderings

7

Licences

8

Lombok : MIT License Lombok-pg : MIT License

Guava : Apache License 2.0

Commons : Apache License 2.0

@ExtensionMethod({ Object.class, MyOtherClass.class })public class DogWithExtension {

public void foo() { String s1 = "toto"; s1.print(); // toto

String s2 = null; s2.print(); // null }}

class MyOtherClass { public static <T> void print(final T value) { System.out.println(value); }}

L

On peut mettre autre chose qu’un "Object", par exemple un "Arrays" , un "Dog" , etc.

9

Extension avec valeurs

@ExtensionMethod({ Object.class, MyOtherClass.class })public class DogWithExtension {

public void foo() { String s1 = "toto"; s1.print(); // toto

String s2 = null; s2.print(); // null s2.print("vide"); // vide }}

class MyOtherClass { public static <T> void print(final T value) { System.out.println(value); }

public static void print(String value, String other) { if (value == null || value.isEmpty()) { System.out.println(other); } else { System.out.println(value); }

9

Extension avec valeurs

L

long start = new Date().getTime();

foo(); // traitement long (ou pas)

long end = new Date().getTime();

long duration = end - start; // 11 ms

Java

5 5< Chrono >

10

Stopwatch sw = new Stopwatch();sw.start();

foo(); // traitement long (ou pas)

sw.stop();long duration = sw.elapsedMillis(); // 11 ms

G

Gua

va

long nano = sw.elapsedTime(NANOSECONDS); // 11179739 nslong micro = sw.elapsedTime(MICROSECONDS); // 11179 uslong millis = sw.elapsedTime(MILLISECONDS); // 11 ms

http://blog.developpez.com/guava/p11160/base/le-stop-watch-de-guava/

CharMatcher

11

Impl

12

public class Dog implements Comparable<Dog> {


...

@Override public int compareTo(Dog dog) { return ...; }

implements List ? aie aie aie

5

Impl

12

@AutoGenMethodStubpublic class Dog implements Comparable<Dog> {


...

L

List<Dog> dogs2 = newArrayList( new Dog("Rintintin", 45.0, MALE, ...),

new Dog("Pluto", 22.0, MALE, ...),

new Dog("Lulu", 35.6, MALE, ...));

Seco

nde

liste G

[Rintintin, Pluto, Lulu]

[Milou, Rintintin, Volt, Lassie, Pluto, Medor]

Liste 2 : dogs2

Liste 1 : dogs

13

And, or, in…

And, or, in…

13

And,

or,

in... import static com.google.common.base.Predicates.and;

import static com.google.common.base.Predicates.in;

boolean isRintintinInBoth = and( in(dogs), in(dogs2) ) .apply(new Dog("Rintintin"));

true

import static com.google.common.base.Predicates.or;

boolean isTintinInOne = or( in(dogs), in(dogs2) ) .apply(new Dog("Tintin");

false

G

G

[Rintintin, Pluto, Lulu]

[Milou, Rintintin, Volt, Lassie, Pluto, Medor] Li

ste

2 : d

ogs2

List

e 1

: dog

s

Partition, limit

14

Parti

tion

List<List<FullDog>> partition = Lists.partition(dogs, 4);

[Milou, Rintintin, Volt, Lassie]

[Pluto, Medor]

List<FullDog> first4Dogs = newArrayList(Iterables.limit(dogs, 4));

[Milou, Rintintin, Volt, Lassie]

G

GLim

it

Inférence de type

15

Java



Gua

va

public static <E> ArrayList<E> newArrayList() { return new ArrayList<E>();}

http://blog.developpez.com/guava/p11334/collection/inference-de-type-avec-guava

Coût du bloom

16

final List<DogGuava> dogs = Lists.newArrayList();

final Funnel<DogGuava> dogFunnel = new Funnel<DogGuava>() { @Override public void funnel(DogGuava dog, PrimitiveSink sink) { sink.putString(dog.getName()) .putString(dog.getFullName()) .putString(dog.getRace()); }};BloomFilter<DogGuava> bloom = BloomFilter.create(dogFunnel, NB_OF_DOGS, 0.01);

final Random rand = new Random();

Stopwatch sw = new Stopwatch();sw.start();

for (int i = 0; i < NB_OF_DOGS; i++) { final DogGuava dog = new DogGuava(...); dogs.add(dog);}

long duration1 = sw.elapsedTime(MICROSECONDS);

Coût du bloom

16

for (DogGuava dog : dogs) {bloom.put(dog);

}long duration2 = sw.elapsedTime(MICROSECONDS);

boolean inside = dogs.contains(milou);long duration3 = sw.elapsedTime(MICROSECONDS);

Chiens Add to list Add to bloom Recherche

1 828 17 971 430

10 938 26 643 749

100 2 159 21 859 754

1 000 9 312 49 564 1 192

10 000 42 232 126 505 5 613

100 000 156 065 261 168 14 353

1 000 000 1 594 113 775 300 41 904

Pas d’écrasement des getters existants

17

@Datapublic class MicroDog {

private String name; private Integer age;

public String getName() { return "*" + name + "*"; }}

@Testpublic void testGetterExistant() { final String name = "Milou"; final String requiredName = "*Milou*";

final MicroDog dog = new MicroDog(); dog.setName(name);

assertEquals(requiredName, dog.getName());}

Slides en préparation

I/O

todo

public void lireJava6(String from) { InputStream in = null; try { in = new FileInputStream(from); byte[] b = new byte[10000]; while (true) { int r = in.read(b); if (r == -1) break; ... } } catch (Exception e) { ... } finally { if (in != null) { try { in.close(); } catch (Exception e) { ... } } ...

Ress

ourc

es 5< I/O >

public void lireJava7(String from) { try(InputStream in = new FileInputStream(from)) { ... while (true) { ... } }}

Java

7 7< I/O >

Todo

Gua

va G< I/O >

Concurrent / future

todo

Todo

Technology

Soirée Guava et Lombok avec Thierry Leriche